(a) Technical Field
The present invention relates to a liquid crystal display, and more particularly, to a wide viewing angle liquid crystal display with a high response speed.
(b) Discussion of the Related Art
Liquid crystal displays are a widely used example of flat panel displays. A liquid crystal display includes two substrates on which field generating electrodes such as pixel electrodes and common electrodes are formed, and a liquid crystal layer which is interposed between the substrates. In the liquid crystal display, voltages are applied to the field generating electrodes so as to generate an electric field over the liquid crystal layer. Then the alignment of liquid crystal molecules of the liquid crystal layer is determined by the generated electric field. Accordingly, the polarization of incident light is controlled, and an image may be displayed thereby.
A vertical alignment (VA) mode liquid crystal display is an example of a liquid crystal display in which the long axis of the liquid crystal molecules remain perpendicular to the upper and lower display panels when no electric field is applied thereto. VA liquid crystal displays have a high contrast ratio and a wide reference viewing angle (defined as the viewing angle at which the contrast ratio is equal to 1:10 or as the limit angle for the inversion in luminance between the grays).
The wide viewing angle of the vertical alignment (VA) mode liquid crystal display (LCD) can be realized by either cutouts or protrusions formed on the field generating electrodes. Since the cutouts or protrusions can determine the inclination directions of liquid crystal molecules, cutouts and protrusions may be arranged along the field generating electrodes to thereby widen the reference viewing angle. However, existing techniques of forming the cutouts or protrusions in the vicinity of the pixel and the common electrodes can complicate the manufacturing process for the liquid crystal displays. Furthermore, in vertical alignment (VA) mode liquid crystal displays having the protrusions or cutouts, the liquid crystal molecules close to the cutouts or protrusions are controlled to a greater extent than those liquid crystal molecules that are farther away from the cutouts or protrusions thereby lowering the response speed of the display device.
In order to overcome such a problem, it has been suggested that a direction controlling electrode be formed under the cutouts of the pixel electrode so as to divide one pixel into two or more pixel electrodes, thereby realizing a wide viewing angle. However, when forming the direction controlling electrode, a wide viewing angle is obtained only when the voltages applied to the pixel electrode, the common electrode, and the direction controlling electrode satisfy predetermined conditions. Accordingly, different signals should be input into two or more pixel electrodes and the direction controlling electrode for each image frame. However, this causes the driving of the liquid crystal display to be complicated.